I am working on a task where I have data about patients with the variables reportid (date of treatment), type (T for Treatment, S for Symptoms, C for conditions) and a variable names with the assigned name of the treatment, symptom or condition. I have to analyze if there are rules concerning the occurrence of treatments and symptoms.
First of all I created two subsets of the data, each for Treatment and Condition. Then I concatenated the data frame into transaction format and then I wanted to apply the apriori algorithm, but I get the error: "Error in validObject(.Object) : invalid class “ngCMatrix” object: row indices are not sorted within columns". I have no clue how I can sort the data within the columns. I would appreciate if someone of you could help me with my problem. Thank is advance :)
